Underfloor Heating Calculator
Calculate pipe length and circuits for underfloor heating.
The Underfloor Heating Calculator is a free tool designed for construction professionals and enthusiasts. Calculate pipe length and circuits for underfloor heating. Instantly get the required materials broken down by purchase units, with an option to add a wastage allowance so you never run short on site.
Inputs
Result
Result
How to Use This Calculator
- Identify the required flow rate in liters per minute (L/min) or liters per second (L/s).
- Measure the pipe length in meters, including vertical runs.
- Enter the nominal or internal pipe diameter.
- Add estimated minor losses (elbows, valves) if known.
- Click 'Calculate' to get fluid velocity, head loss and recommended diameter.
Frequently Asked Questions
For domestic installations, do not exceed 1.5 m/s in distribution pipes and 2 m/s in collectors. Higher velocities cause noise and erosion.
For a single-family home, the service pipe is usually 25–32 mm, main distribution 20 mm and appliance branches 15–16 mm (½").
Minimum recommended volume is 150–200 litres per occupant for 1-day reserve. For emergency reserves, extend to 2–3 days.